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Life's Irreducible Structure Author(S): Michael Polanyi Source: Science, New Series, Vol

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Life's Irreducible Structure Author(S): Michael Polanyi Source: Science, New Series, Vol Life's Irreducible Structure Author(s): Michael Polanyi Source: Science, New Series, Vol. 160, No. 3834 (Jun. 21, 1968), pp. 1308-1312 Published by: American Association for the Advancement of Science Stable URL: http://www.jstor.org/stable/1724152 Accessed: 15-07-2015 16:00 UTC Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at http://www.jstor.org/page/ info/about/policies/terms.jsp JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. American Association for the Advancement of Science is collaborating with JSTOR to digitize, preserve and extend access to Science. http://www.jstor.org This content downloaded from 128.103.149.52 on Wed, 15 Jul 2015 16:00:49 UTC All use subject to JSTOR Terms and Conditions whereas the second is of the machino type. By shifting our attention, we may sometimes change a boundaryfrom one type to another. Life's IrreducibleStructure All communicationsform a machine type of boundary, and these boundaries form a whole hierarchy of consecutive Live mechanismsand informationin DNA are boundarzr levels of action. A vocabulary sets boundary conditions on the utterance conditionswith a sequenceof boundariesabove them. of the spoken voice; a grammar har- nesses words to form sentences, and the sentences are shaped into a text which Michael Polanyi conveys a communication. At all these stages we are interested in the bounda- ries imposed by a comprehensiverestric- tive power, rather than in the principles If all men were exterminated, this So the machine as a whole works harnessed by them. would not aSect the laws of inanimate under the control of two distinct prin- nature. But the production of machines ciples. The higher one is the l?rinciple would stopS and not until men arose of the machine's design, and this haru L;ving Mechanisms Are Classed again could machines be formed once nesses the lower one, which consists in with Machines rnore.Some animals can produce tools, the physical-chemical processes orl lbut only men can construct machines; which the machine relies. We com- From machines we pass to living machines are human artifacts, made of monly form such a two-leveled struc- beings, by remembering that animals inanimate material. ture in conducting an experiment; but move about mechanically and that they The Oxford Dictionary describes a there is a difference between construct- have internal organs which perform tnachine as 6'an apparatus for applying mg* a macnlne. * ancl. rlgglng* . up an ex- functions as parts of a machine do tnechanicalpower, corlsistingof a num periment. The experimenter imposes functions which sustain the life of the lber of interrelated pa.rts, each having restrictions on nature in order to organism,much as the proper function- a definite function." It might be, for obsenre its behavior under these restric- ing of parts of a machine keeps the e;ample, a machine for sewing or printS tions, while the constructor of a ma- machine going. For centuries past, the ing. Let us assume that the power driv- chine restrictsnature in order to harnes workings of life have been likened to ing the machine is built in, and its workings.- But we may borrow a the working of machines and physiology lisregard the fact that it has to be re- tetm from physics and describe both has been seeking to interpret the orga- newed from time to time. We can say, these useful restrictions of llature as nism as a complex network of mecha- then, that the manufacture of a ma- the imposing of boundaryconditions on nisms. Organs are, accordingly, defined chine consists in cutting suitably shaped the laws of physics and chemistrye by their life-preservingfunctions. parts and fitting them together so that Let me enlarge on this. I have ex- Any coherent part of the organism their joint mechanical action should emplified two types of boundaries. In is indeed puzzling to physiology and serve a possible human purpose. the machine our principal interest lay also meaningless to pathology-until The structure of machines and the in the eSects of the boundary condi the way it benefits the organism is dis- working of their structure are thus tions, while in an experimental setting covered. And I may add that any de- shaped by man, even while their ma- we are interested in the natural l?roc scription of such a system in terms of terial and the forces that operate them esses controlled by the boundaries. its physical-chemical topography is obey the laws of inanimate nature. In There are many common examples of meaningless,except for the fact that the constructing a machine and supplying both types of boundaries. When a description covertly may recall the it with I?ower,we harness the laws of saucepan bounds a soup that we are system's physiological interpretation- nature at work in its material and in its cooking, we are interested in the soup; much as the topography of a machine driving force and make them serve our and, likewise, when we observe a re- is meaningless until we guess how the purpose. action in a test tube, we are studying device works, and for what purpose. This harness is not unbreakable;the the reaction, not the test tute. The In this light the organism is shown strtlcture of the machine, and thus its reverse is true for a game of chess. The to be, like a machine, a system which working, can break down. But this will strategy of the player imposes bound works according to two different prin- not affect the forces of inanimate aries on the several moves, which folZ ciples: its structureserves as a boundary nature on which the operation of the low the laws of chess, but our interest condition harnessingthe physical-chemi- machine relied; it merely releases them lies in the boundaries-that is, in the cal processes by which its organs per- from the restriction the machine im- strategy, not in the several moves as form their functions. Thus, this system posed on them beforc it broke down. exemplificationsof the laws. And simi- may be called a system under dual larly, when a sculptor shapes a stone control. Morphogenesis,the process by The author is a former Fellow of Merton Col- lege, Oxford, and Emeritus Professor of social or a painter composes a painting, our which the structureof living beings de- studies at the University of Manchester, where interest lies in the boundaries imposed velops, can then be likened to the he had previously held the Chair of Physical Chemistry. His present address is 22 Upland on a material, and not in the material shaping of a machine which will act Park Road, OxfordSEngland. This article is an itself. as a boundaryfor the expandedversion of a paper presented20 Decem- laws of inanimate ber 1967 at the New York meeting of the AAAS. We can distinguish these two types nature. For just as these laws serve the The-Xrst half of the article was anticipatedin a paper published in the August 1967 issue of of boundaries by saying that the Erst machine, so they serve also the devel- Chemical and Engineering lVelvs. represents a test-tube type of boundary oped organism. 1308 SCIENCE, VOL. 160 This content downloaded from 128.103.149.52 on Wed, 15 Jul 2015 16:00:49 UTC All use subject to JSTOR Terms and Conditions A boundary condition is always ex- tive basic bindings having the same DNA Acts as a Bluepnnt traneousto the process which it delimits. probability of occurrence. In Galileo's experimentson balls rolling Let us be clear what would happen But there remains a fundamental down a slope, the angle of the slope in the opposite case. Suppose that the point to be considered. A printed page was not derived from the laws of me- actual structure of a DNA molecule may be a mere jumlbleof words, and chanics, but was chosen by Galileo. were due to the fact that the bindings it has then no information content. So And as this choice of slopes was ex- of its bases were much stronger than the improbability count gIves the pos- traneous to the laws of mechanics, so the bindings would be for any other sible, rather than the actual, informa- is the shape and manufacture of test distributionof bases, then such a DNA tion content of a page. And this applies tubes extraneous to the laws of chem- molecule would have no information also to the information content attrib- istry. content. Its codelike character would uted to a DNA molecule; the sequence The same thing holds for machine- be effaced by an overwhelming redun- of the bases is deemed meaningful only like boundaries; their structure cannot dancy. because we assume with Watson and be defined-in terms of the laws which We may note that such is actually the Crick that this arrangement generates they harness. Nor can a vocabulary case for an ordinarychemical molecule. the structure of the oSspring by en- determine the content of a text, and Since its orderly structure is due to a dowing it with its own information so on. Therefore, if the structure of maximum of stability, correspondingto content. living things is a set of boundary con- a minimum of potential energy, its This brings us at last to the point that ditions, this structure is extraneous to orderlinesslacks the capacity to function I aimed at when I undertook to analyze the laws of physics and chemistry as a code.
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